Galaxy Formation through Winds, Infall and Merger: Learning from Galactic Archaeology

摘要

Here we show how we can dig the information on the prominent processes in galaxy evolution out of stellar records. Two studies are presented. First, the observed indication that the elemental abundance gradient evolves with cosmic time in the Milky Way disk is shown to be evidence of large-scale winds that once enriched the whole disk, which set up the steep abundance gradient in the inner disk several Gyr ago. Secondly, we show that evidence of a major merger in the SMC is imprinted in its age-metallicity relation as a dip in [Fe/H]. Our theoretical models predict that the major merger with a mass ratio of 1:1 to 1:4 occurred at —7.5 Gyr ago in the SMC.